[PATCH v2 06/17] x86/resctrl: Introduce interface to display number of ABMC counters

[Babu Moger]

The ABMC feature provides an option to the user to pin (or assign) the
RMID to the hardware counter and monitor the bandwidth for a longer
duration. There are only a limited number of hardware counters.

Provide the interface to display the number of ABMC counters supported.

Signed-off-by: Babu Moger <babu.moger@xxxxxxx>

---
v2: Changed the field name to mbm_assignable_counters from abmc_counters.
---
 Documentation/arch/x86/resctrl.rst     |  4 ++++
 arch/x86/kernel/cpu/resctrl/monitor.c  |  4 ++++
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 17 +++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
index ecc6c65bdaca..73eeb50fd0b5 100644
--- a/Documentation/arch/x86/resctrl.rst
+++ b/Documentation/arch/x86/resctrl.rst
@@ -264,6 +264,10 @@ with the following files:
 	    # cat /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config
 	    0=0x30;1=0x30;3=0x15;4=0x15
 
+"mbm_assignable_counters":
+	Available when ABMC feature is supported. The number of assignable bandwidth
+	monitoring counters available.
+
 "max_threshold_occupancy":
 		Read/write file provides the largest value (in
 		bytes) at which a previously used LLC_occupancy
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index a6c336b6de61..fa492ea820f0 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -823,6 +823,10 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 			resctrl_file_fflags_init("mbm_local_bytes_config",
 						 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
 		}
+
+		if (rdt_cpu_has(X86_FEATURE_ABMC))
+			resctrl_file_fflags_init("mbm_assignable_counters",
+						 RFTYPE_MON_INFO);
 	}
 
 	l3_mon_evt_init(r);
diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 3e233251e7ed..53be5cd1c28e 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -811,6 +811,17 @@ static int rdtgroup_rmid_show(struct kernfs_open_file *of,
 	return ret;
 }
 
+static int rdtgroup_mbm_assignable_counters_show(struct kernfs_open_file *of,
+						 struct seq_file *s, void *v)
+{
+	struct rdt_resource *r = of->kn->parent->priv;
+	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
+
+	seq_printf(s, "%d\n", hw_res->mbm_assignable_counters);
+
+	return 0;
+}
+
 #ifdef CONFIG_PROC_CPU_RESCTRL
 
 /*
@@ -1861,6 +1872,12 @@ static struct rftype res_common_files[] = {
 		.seq_show	= mbm_local_bytes_config_show,
 		.write		= mbm_local_bytes_config_write,
 	},
+	{
+		.name		= "mbm_assignable_counters",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= rdtgroup_mbm_assignable_counters_show,
+	},
 	{
 		.name		= "cpus",
 		.mode		= 0644,
-- 
2.34.1